1. Field of the Invention
The present invention relates to a limit switch, especially to a limit switch used in a linear actuator.
2. Description of Related Art
A linear actuator is widely adopted in the medical equipment such as a hospital bed or electric chair or other fields where a retractable movement is required.
A conventional linear actuator includes a drive unit, a transmission device, a retractable tube and two limit switches. When the retractable tube is forwardly moved and in contact with one of the limit switches, the power supply for the forward movement of the drive unit is terminated, thereby only allowing the retractable tube to be backwardly moved; on the other hand, when the retractable tube is backwardly moved and in contact with the other limit switch, the power supply for the backward movement of the drive unit is terminated, thereby only allowing the retractable tube to be forwardly moved. As such, the forward and backward movements of the retractable tube can be controlled through the two limit switches while supplying electric power.
Please refer to FIG. 1, which is a schematic view showing the installation of the limit switch of a conventional linear actuator. A limit switch (1a) of the linear actuator is disposed on a support plate (2a), and the support plate (2a) is further installed with a diode (3a) and a wire (4a). The limit switch (1a) takes advantage of the rectifying function provided by the diode (3a) to allow the current to only flow in one direction and to block the current flowing in the reverse direction. In assembly, external connection pins (5a) of the limit switch (1a) are protruded from the support plate (2a), then the diode (3a) and the wire (4a) are electrically connected to the connection pins (5a) of the limit switch (1a) with a manual welding manner, such that the signal of the limit switch (1a) and the diode (3a) is enabled to be transferred to a control unit through the wire (4a).
However in the mentioned structure, the manual welding manner for connecting the limit switch (1a) and the diode (3a) is time consuming, labor consuming and not easy to be positioned, thereby causing difficulty in assembly.
In view of the mentioned disadvantage, the applicant of the present invention has devoted himself for providing a novel design to improve the mentioned disadvantage.